1. Field of the Invention
The present invention relates to a tool path display apparatus for machine tools and, more particularly, to a display apparatus capable of visually grasping the correspondence between the position of a tool tip in a three-dimensional path and the position in a time axis of time-series waveform data for each of axes.
2. Description of the Related Art
Some currently-used numerical controllers for controlling machine tools have a function of displaying a specified path or a function of displaying the path in which the tool actually moved.
Japanese Patent Application Laid-Open No. 7-5908 discloses a measuring/monitoring apparatus that obtains a position signal etc. from appropriate points in a controller controlling the position and speed for machine operation. The measuring/monitoring apparatus creates time-series data by sampling the obtained signals at specified intervals, graphically displays a motion path in real time by calculating the time-series data, thereby enabling the monitoring of the controller and the measuring of the precision of the motion path.
Japanese Patent Application Laid-Open No. 2008-9637 discloses a display method of an NC program for controlling the motion of each drive axis. The NC program calculates and displays the target motion position for each drive axis, the motion path to the target motion position, and the feedrate. The actual feedrate and its acceleration/deceleration at an arbitrary machining position and elapsed time can be obtained from the display, so the state of the NC program can be recognized.
A 5-axis machine tool has a rotation axis as a drive axis, so it is difficult to intuitively grasp the correspondence between the motion of each of the drive axes and the motion of the tool tip. Accordingly, when a particular position on a machined surface is defective, it is difficult to identify the part corresponding to the defective part even by measuring the waveform of each drive axis that is working.
Japanese Patent Application Laid-Open No. 7-5908 above proposes a technique for calculating time-series measurement data and displaying the tool path, but does not propose a method of determining characteristic points. Japanese Patent Application Laid-Open No. 2008-9637 proposes a technique for evaluating the validity of an NC program, but does not propose a specific evaluation method using the actual position data of each drive axis or does not refer to the association between the tool path and the waveform of each drive axis.